Third COVID-19 vaccine dose beneficial for most immunocompromised patients
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Key takeaways:
- A third dose may bring these patients protection that is equal to healthy patients.
- Those with lymphoid disease, chronic renal disease or receiving rituximab or other B cell-targeting therapies had a lower vaccine response.
A third dose of COVID-19 vaccine can boost serological and T-cell response among most patients who are immunocompromised, according to data published in The Lancet Rheumatology.
“Pivotal trials of COVID-19 vaccines excluded patients who were clinically susceptible with an immunocompromised state, yet more than 60% of people older than 65 years live with one or more such chronic disease,” Carl S. Goodyear, PhD, of the University of Glasgow, in the United Kingdom, and colleagues wrote. “A crucial contemporary question concerns the effect of multiple vaccine exposures.”
To test the value of additional COVID-19 vaccine doses among patients with immunodeficiencies, Goodyear and colleagues conducted a prospective, open-label, randomized controlled phase 3 study across 11 U.K. hospitals. The study was conducted between Aug. 4, 2021, and March 31, 2022, and included 804 immunocompromised adults who had demonstrated inadequate or no response to two doses of COVID-19 vaccines.
Participants were randomly assigned in a 1:1 ratio to receive a third vaccine dose of either the BNT162b2 (Pfizer, BioNTech) or mRNA-1273 (Moderna) formulations. For patients with lymphoid malignancies, NVX-CoV2373 (Novavax) was also a potential vaccine option.
The primary outcome was vaccine-specific immunogenicity 21 days after the third dose vs. before, measured via anti-SARS-CoV-2 spike antibody concentrations and T-cell responses to SARS-CoV-2 spike peptides.
According to the researchers, anti-SARS-CoV-2 spike antibody titers were significantly higher at 21 days (median: 1,384 AU/mL [IQR: 4.3-7,990]), compared with baseline figures from before the third dose (median: 11.5 AU/mL [IQR: 0.4-63.1]).
Among the 423 patients designated as low responders at baseline, 90% demonstrated antibody concentration increases of greater than 400 AU/mL. Meanwhile, of the 308 participants with no response at baseline, 54% had no response after the third dose. Notable cohorts with lower antibody response included participants with lymphoid disease, chronic renal disease and those receiving rituximab (Rituxan, Genentech) and other B cell-targeting therapies.
Following the third dose, 80% of the 616 participants with complete data had T-cell responses detectable using the Oxford Immunotec modified T-Spot Discovery SARS-CoV-2 assay, according to the researchers.
“Although not a definitive surrogate, this suggests that patients who are immune susceptible might have a level of protection that equates to the healthy population with additional vaccines,” Goodyear and colleagues wrote. “Conversely, only a modest proportion of those who did not respond to two doses of COVID-19 vaccines generated any detectable serological response to a third dose, with only 58 (19%) reaching the concentrations of antibodies seen in healthy individuals, suggesting that a subset of patients remain at high risk.”
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